Container for safety blasting explosives



pnl 2l, 1953 G. P. slLLlT-ro ErAL CONTAINER FOR SAFETY BLASTING ExPLosrvEs Filed Jan. 22, 1948 INI/ENTORS GEORGE PERCY SILLITTO DONBLIDgYGE-LQRGE BSHCROFT ATTORNEY Patented Apr. 2l, 1953 UNITED STATES PATENT OFFICE CONTAINER FUR SAFETY vBELASTING EXPLOSIVES ApplicationJanuary 22, 1948, SeralNo.3;'158- yIn GreatBritain Februaryfi, 1947 4 Claims.

The present invention relates to containers for Safety blasting explosivesand to the provision of safety-sheathed blasting explosive cartridges formed from safety blasting explosives in said containers.

-By the phrase safety-sheathed blasting explosive cartridges is meant a cartridge of a detonating explosive made from a composition including a suitable proportion of ingredients adapted to minimise its capacity for igniting fire-damp air mixtures or coal-dust air mixtures when it detonates and which is provided along its y,cylindrical surface with an external safety sheath that comprises -amequenching or cooling ingredients.

In safety-sheathedl detonating explosive cartridges the explosive composition customarily includes ammonium nitrate as one of its power producing ingredients, one or more compounds capable of vapcrisation, fusion or thermal decomposition with absorption of heat as a flame quenching or cooling ingredient, and the safetysheath also comprises .one or more compound of the latter description. It is also the practice for theexplosive cartridge proper to be provided with a waterproofed paper wrapper and for this portion of the sheathed cartridge to comply with the official gallery tests for permitted explosives.

The blanketing eiect of carbon dioxide on the flame of the, explosive and its innocuous character render it a particularly desirable gas to be generated'by the sheathing material when the detonation takes place. sheathing materials consisting essentially of various more or less insoluble metal carbonates have been tried with varying results. Of the carbonates sodium bicarbonate is 4the most effective and is the cornpound generally employed in practice in this country, notwithstanding the fact that it is slightly soluble in water and must be carefully separated by a waterproof wrapping from the explosive cartridge, since it would otherwise react with the ammonium salt present in the explosive, to produce ammonium bicarbonate which gives rise to loss of ammonia and carbon dioxide.

For example, vBritish specification No. 416,586 discloses inter alia a flexible safety sheathing material for blasting explosives consisting of name quenching felt material in sheet form and comprising a uniform mixture of a fibrous binding-materiaranda vprcponderating -proportion of a cooling salt or mixtures of cooling salts.

In British Patent No. 584,848 there is claimed inter alia a safety sheathed blasting explosive cartridge wherein the said sheath comprises a mixture .of one molar part of a metal carbonate not freely` soluble in water and a third of two molar parts of a dry hydrated form of alumina.

The object of the present invention is to provide in a simple and convenient manner a .conftainer for a safety blasting explosive which shall embody in itself the three essentials required in the covering of a safety-sheathed blasting explosive cartridge, namely the water-proofed paper wrapper for the cartridge proper, the flame quenching felt material and the external unwaxed paper wrapping, thereby permittingsafety sheathed blasting explosives to be more advantageously manufactured.

According to the present invention a container for a safety blasting explosive consists internallyy of waxed paper and externally of unwaxed paper, the waxed and unwaxed papers being separated from one another by flame quenching felt vmaterial and Vis formed from va length of quenchingfelt material cemented at one end to a length o f unwaxed paper andat its other end to a length of waxed paper, wherein the width of the. felt material and unwaxed paper correr-l sponds substantially to the length of explosive charge to'beheld by the container and the width of the waxed. paper is such that it projects at each side E,of the felt material to enable the endclosures of the container to be formed and wherein the lengths of the feltmaterialand waxed and unwaxedpapers are such as to permit the desired numbers of layers of each of these to be provided- If desired the unwaxed paper may be so cemented-to the ame quenching felt as to leave only a free narrow longitudinal strip of unwaxed paper sufficient to forma sealed cylinder.

For explosive compositions containing ammonirum nitrate there must, be at least one complete layer of waxed paper in order to prevent any ncontact betweensaid explosive and the bicarhonate containing felt. 'Ihe number of felt` layersdepends .upon .thedesiredratio of quantity. oi felt-to explosive. It is t usually suiiicientV for the container to..-be provided with only one Lex, ternal layer of ,unwaxedpaper It is often considered desirable for the inside of Kthe container to be provided witha layer of- Wax so `,as to proyidefa moisture resistant layerI between-the explosive-and the atmosphere. I t

may be desirahleior the ends-formed by=;fo1dmgstantially the same width as itself so that the i waxed paper forms the internal-surface of the f cylinder and the unwaxed paper forms the-ex?y end of the exposed waxed paper. If desired the inside surface-"ofthe thus formed can be given acoating of waxby the spraying thereon of a melted wax composition.

According to the inventiontne method forfvhe production of safety-sheathed blasting explosive cartridges comprises introducing a charge f container .c 10 ternal surface of the cylinder, and folding Vone safety blasting explosive.. into a container con- 'I ssting internally of waxed paper and externally of unwaxed paper separated from one another by llame quenching felt material and formed from a length of flame quenching felt material cementedat one "end'to a length o funwaxedpaper and at the4 other end tol aL length ofl waxed paper whereinv the width of the felt material and unwaxed paper corresponds substantiallyjt'o the length of explosive charge tobe held by the` container and the width of the waxed paper issuch Athat it projects at each side of thefelt material to enable the end-'closures of the container to be formed and wherein the-lengths of the felt material and waxes and unwaxed papers are such as to permitthe desired number of layers of each of these to be produced.

' By Way of example the invention is illustrated in the diagrammatic drawing Vaccompanying the specification whereof each of Figs. 1 and '2 Yis a plan view of a length of name quenching felt material cemented at one end to unwaxed paper and at its other end to waxed paper, Fig'. 3 isa longitudinal section through a cylinder formed by rolling the felt material-paper lengths shown `in Fig. 1 or Fig. 2, .andfFig 4'is a longitudinal section through a container formed'by folding one of the projections in the cylinder shown in Fig. 3. Referring to the drawing, I isa p iece of'ame quenching felt material 6% inches wi'de'and 12%;v incheslong and consistir'ig approximatelyof 85 per 'cent sodium bicarbonate and 15 per cent'wood pulp, 2 is a piece of waxed'manilla `paper, 8 1g inches long and 81/4 inches wide, 3 is apiece :of unwaxed paper6% inches wide'and 61A inches long. In Figs. 1 and 2, the felt materialjisfshown on'top ofthe papers 2"and According to the embodiment shown :in Fig.` lfonly ,a narrowedge ofthe unwaxed papery 3 and the felt material'l are 'shown cemented together at' 4 lwhereas ac-Y cording to the embodiment shown in Fig; V2 rmost ofthe 'unwaxed paper 3 cemented 'at 5 to the" felt material I leaving" only aharrow strip of free unwaxed paper. Ineac'h'embo'dim'ent the waxed` paper 2 i's shown cemented onlyv b/yan'arrovv edge 6to the felt material- I The Awaxed paper'Z'is s0 positionedr withl respect'ito V the felt material jIj asy te leave projections L "If atieachside of 'the' feltj strip I. The felt vvmaterial paper 'lengths' are' rolled-into cylinders of 11%; inches internal diameter in such a way that'the waxed paper 2 is first" formed' into cylindricalfshape'an'd that the felt material at 6 is in due 4course between 4waxed paper-surfaces.- When-the projection "I' of thev cylinder shown in Fig.- 3- is suitably `folded a 4 nished container is formed as shown in Fig. 4. The external diameter of the nished container as shown in Fig. 4 is approximately lfl inches. This container has two layers of waxed paper 2, three vlayers of felt material I. and one llayer of unwaxed' paper 3. Into'` the finished container shown in Fig. 4, 4 ozs. of Polar Viking composition (Home Oice Permitted List) can be introduced whereupon the projection 'I is folded. f Polar Viking is a nitroglycerine powder explosive suitable for use in coal mines in which fire -damp or coal dust may be present. If desired, the folded ends of the closed container can be given a spray-coatingof wax.

" `We claim: 1. A safety blasting explosive charge container vconsisting internally of a length of waxed paper sheet and externally of a length of unwaxed paper sheet, the waxed and unwaxed paper sheets being separatedonerfrom the other by a name quenching felt sheet, said flame quenching felt sheet comprising a uniform mixture of a fibrous binding agent and a preponderating proportion of at least one powdered flame cooling compound, and having at one end the length of unwaxed paper sheet cemented across its width, and at its other end the length of waxed paper sheet cemented across its width, wherein the width of the sheet of flame quenching felt material and unwaxed paper correspond substantially to the length of `the explosiveV charge to be held by the container and the Width of the waxed paper is such that it projects at each side of the felt material and thereby provides end-closure means, and wherein the joined lengths of the felt material, waxed, and Vunwaxed sheets which comprise the connes of the said'container.- are in a desired number of layers of each ofthe same.

2. A-container for a safety blasting explosive as set forth in claim 1 wherein the inside of the container is provided with a layer of wax.

3. A method for the production of a container for a safety blasting explosive which comprises fashioning into 'a cylinder a length of flame quenching felt material cemented at one end to a length of waxed paper having a width'such that it projects at each side ofthe felt material and cemented at its other end to a length of unwaxed paper substantiallyfthe same width so that the waxed paper forms the internal surface of the cylinder and the unwaxed paper forms the external surface of the cylinder, and folding one end of the projecting waxed paper.

4. A method as set forth in claim 3 wherein the inside surface of the container formed is coated by spraying thereon a melted Wax compo- GEORGE PERCY SILLIT'IO.

DONALD GEORGE ASHCROFI.

Great Britain Aug. 25, 1939 

1. A SAFETY BLASTING EXPLOSIVE CHARGE CONTAINER CONSISTING INTERNALLY OF A LENGTH OF WAXED PAPER SHEET AND EXTERNALLY OF A LENGTH OF UNWAXED PAPER SHEET, THE WAXED AND UNWAXED PAPER SHEETS BEING SEPARATED ONE FROM THE OTHER BY A FLAME QUENCHING FELT SHEET, SAID FLAME QUENCHING FELT SHEET COMPRISING A UNIFORM MIXTURE OF A FIBROUS BINDING AGENT AND A PREPONDERATING PROPORTION OF AT LEAST ONE POWDERED FLAME COOLING COMPOUND, AND HAVING AT ONE END THE LENGTH OF UNWAXED PAPER SHEET CEMENTED ACROSS ITS WIDTH, AND AT ITS OTHER END THE LENGTH OF WAXED PAPER SHEET CEMENTED ACROSS ITS WIDTH, WHEREIN THE WIDTH OF THE SHEET OF FLAME QUENCHING FELT MATERIAL AND UNWAXED PAPER CORRESPOND SUBSTANTIALLY TO THE LENGTH OF THE EXPLOSIVE CHARGE TO BE HELD BY THE CONTAINER AND THE WIDTH OF THE WAXED PAPER IS SUCH THAT IT PROJECTS AT EACH SIDE OF THE FELT MATERIAL AND THEREBY PROVIDES END-CLOSURE MEANS, AND WHEREIN THE JOINED LENGTHS OF THE FELT MATERIAL, WAXED, AND UNWAXED SHEETS WHICH COMPRISE THE COMFINES OF THE SAID CONTAINER, ARE IN A DESIRED NUMBER OF LAYERS OF EACH OF THE SAME. 